Auto racing star Danica Patrick talks to Dave about her first win in an IndyCar race when she visits the Late Show with David Letterman, Wednesday, April 23, 2008 JEFFREY R STAAB CBS

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Team co-owners Bobby Rahal,left, and David Letterman watch from Bertrand Baguette's pit box during the 95th running of the Indianapolis 500, Sunday, May 29, 2011. Matt Kryger

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2013 INDY 500 winner Tony Kanaan, entices Late Show host David Letterman to touch the Borg-Warner Trophy during Monday's 6/3 show taping in New York. John Paul Filo

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MUNCIE, Ind.: Dorothy Mengering, left, glances lovingly over at her son, TV show host David Letterman, as he wipes his eye while laughing at being the brunt of a joke during the dedication ceremonies of Ball State University's David Letterman Communication and Media Building in Muncie on Friday, September 7, 2007. Charlie Nye Indianapolis Star

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2012 Kennedy Center Honoree David Letterman, and his wife, Regina, arrive at the Kennedy Center for the Performing Arts for the 2012 Kennedy Center Honors Performance and Gala Sunday, Dec. 2, 2012 at the State Department in Washington. (AP Photo/Kevin Wolf) Kevin Wolf AP